Found in a 1966 documentation, this “coin finder” uses components from the era operating at 2.1 MHz. The circuit uses an audio amplifier for detection.
Touching the sensor with your fingers, this circuit produces a machine gun sound. The circuit must...
August 2017 - STMicroelectronics' BlueCoin development environment is available at Mouser...
We found this circuit in an old documentation. Its purpose is to turn on warning lights when the...